claims depot shelf
The Hubble Tension
Formal claims (Lean)
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On the paper's own terms, the central discovery is a negative result turned positive: an early-universe modification cannot remove the DESI late-time signal. In the full-data fit of the EDE-CPL model (CMB distance priors, DESI DR2 BAO, Pantheon+ supernovae with the SH0ES subsample), the CPL parameters are constrained to $w_0 = -0.85 \pm 0.06$ and $w_a = -0.56 \pm 0.23$, a clear departure from the
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On the paper's own terms, the central discovery is a separation between statistical fit and dynamical behavior. All four emergent models, whose dark-energy or curvature terms switch on through a hyperbolic-tangent-type function, fit the low-redshift expansion data well enough to remain viable alternatives to $\Omega_k$-\Lambda CDM, with PEDE named as the best candidate by AIC and BIC in the abstra
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For an axisymmetric Bianchi type I background with freely decaying shear and isotropic pressure, the fractional luminosity-distance quadrupole AD(z) is fully determined through relative order z^2 by the present directional expansion contrast BH0 and the background deceleration and jerk parameters: AD(z) = -BH0 + (2q0 - 1) BH0 z / 2 + (5 - q0 - 18q0^2 + 6j0) BH0 z^2 / 12 + O(z^3, BH0^2). The formul
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The paper's central claim is that quantum corrections derived from Weyl-Wigner phase-space mechanics can dissolve the Hubble tension. Starting from a minisuperspace action and the Wheeler-DeWitt equation, it identifies the classical potential as a sum of powers of the scale factor and computes the effective quantum potential induced by a sinusoidal Wigner function W(x,k;τ)=g(x;τ) sin(μ k x). Each
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The central claim is that the entropy-area relation with a scale-dependent exponent Δ(x)=Δ0+Δ1/ln x, where x=(H1/H)^2, when fed into the gravity-thermodynamics first law on the apparent horizon, yields an exact analytic Hubble rate H(z). Combined fits to Hubble-rate measurements, type Ia supernova distances, baryon acoustic oscillations, and CMB shift parameters give H0 = 69.27^+0.62_-0.65 km/s/Mp
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The central discovery is that a cosmological model in which the Gauss-Bonnet correction to the Wald entropy of the apparent horizon is sourced by the astrophysical history of black-hole formation and mergers fits the combined early- and late-Universe data better than ΛCDM, with the coupling parameter Cn = 0.435^{+0.150}_{-0.132}, a ~3σ phantom-side deviation from zero. The mechanism preserves the
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The central discovery is that a cosmological model in which the Gauss-Bonnet correction to the Wald entropy of the apparent horizon is sourced by the astrophysical history of black-hole formation and mergers fits the combined early- and late-Universe data better than ΛCDM, with the coupling parameter Cn = 0.435^{+0.150}_{-0.132}, a ~3σ phantom-side deviation from zero. The mechanism preserves the
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The central discovery is a simple ratio identity: with the CMB acoustic angular scale and the sound horizon fixed, a fractional increase in H0 equals the fractional increase in the dimensionless distance integral I ≡ ∫_0^{z★} dz/E(z). The paper splits I into a low-redshift part I<, directly constrained by data, and a high-redshift part I> that is not, and shows that Gaussian Process reconstruction
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In a Planck-calibrated flat LambdaCDM background, matching the SH0ES measurement of H0 through a void-induced local expansion excess requires a present-day enclosed density contrast of about -0.44, roughly 50% deeper than the KBC benchmark of -0.3. A KBC-like void lowers the statistical tension from above 5 sigma to about 2 sigma, and the tension remains below 3 sigma only for voids with depths be
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In a Planck-calibrated flat LambdaCDM background, matching the SH0ES measurement of H0 through a void-induced local expansion excess requires a present-day enclosed density contrast of about -0.44, roughly 50% deeper than the KBC benchmark of -0.3. A KBC-like void lowers the statistical tension from above 5 sigma to about 2 sigma, and the tension remains below 3 sigma only for voids with depths be
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The paper's central claim is that the generalized mass-to-horizon entropy class, despite its additional parameters, is observationally forced back to standard Bekenstein–Hawking thermodynamics: the entropy exponent satisfies |m−1| ≲ 10⁻⁴ when the MHR coupling is fixed and ≲10⁻³ when the coupling is free, and the derived coupling and entanglement amplitude deviate from their ΛCDM values only along
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The paper's central claim is that the generalized mass-to-horizon entropy class, despite its additional parameters, is observationally forced back to standard Bekenstein–Hawking thermodynamics: the entropy exponent satisfies |m−1| ≲ 10⁻⁴ when the MHR coupling is fixed and ≲10⁻³ when the coupling is free, and the derived coupling and entanglement amplitude deviate from their ΛCDM values only along
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The central claim: apparent phantom crossing can arise from a well-defined interacting dark sector, not a fundamental phantom field. In the DADB model, the dark QCD axion's effective potential depends on dark-baryon density; the baryon mass varies as the axion rolls, falling before recombination and rising afterwards. This non-monotonic mass evolution fits the CMB while producing an apparent phant
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The authors claim that the HN c-field dynamics is encompassed by the GCG equation of state through an equivalent modified scalar field theory. Concretely, they construct a mapping between two scalar fields, ϕ (GCG) and φ (c-field-modified), linked by the constraints ċ² = (3/2) y_ϕ² (1 − φ_ϕ²) and H²(φ) = H²(ϕ) − ċ²/3. For a linear rescaling φ(ϕ) = ℓϕ they obtain explicit ρφ(a) and pφ(a) formulas,
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In the phenomenological ξ IDE model the combination ξ + 3w_X is negative for every dataset combination examined, corresponding to energy transfer from dark energy to dark matter; the tightest constraint is ξ + 3w_X = −0.035 ± 0.023 (1.52σ from zero) for CMB + DESI DR2 + CC + Union3, so current data supply only a weak indication of a non-zero dark-sector interaction while Bayesian evidence continue
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The heliosphere acts as a coherent, observer-side optical filter: plasma refractive-index gradients across the heliopause produce a weak-lensing flux enhancement δ_helio of order 0.08 for upwind lines of sight at 550 nm, enough to shift the local distance ladder by several percent and thereby contribute 3–8 percent of the Hubble tension once anisotropy and calibration effects are included.
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When linear dark-energy perturbations are treated consistently, the smooth error-function ECDM model is fully compatible with current precision CMB, BAO and supernova data and simultaneously lowers the Hubble tension relative to flat ΛCDM.
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Joint strong-lensing constraints on the sign-changeable interaction Q = 3 beta H rho_dm q yield best-fit values Omega_dm0 = 0.253^{+0.018}_{-0.004} and beta = -0.83^{+0.10}_{-0.08}. This large negative beta implies dominant energy flow from dark energy to dark matter, producing a constantly accelerating Universe whose deceleration-parameter zero-crossing occurs at z_t = 2.33 rather than the Lambda
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When the scalar potential is purely quadratic (μ=0), the fractional model with dynamically evolving G and H becomes the only variant that is both statistically competitive with ΛCDM and dynamically consistent: it yields an overdamped relaxation timescale τ_rel≈9 Gyr, well-constrained fractional exponents, and late-time cosmographic functions that closely track but do not coincide with those of ΛCD
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A minimally coupled three-form with a Gaussian potential is a viable, competitive description of the cosmic expansion history. It is mildly preferred over ΛCDM precisely for the most tensioned early-plus-late combination (CMB+DESI BAO + Pantheon+SH0ES), becomes neutral for the less-tensioned early-plus-late set, and is disfavoured or inconclusive when early-only or late-only data are used. The dyn
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When a dynamical dark-energy fluid is placed in a Bianchi Type-V spacetime, the residual shear density couples to the expansion history and to linear growth in such a way that simultaneous late-time measurements of distances and structure growth are better accommodated, thereby lowering the statistical tension between local and early-universe determinations of both H0 and S8.
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Coupling H(z) and fσ8(z) through the GR linear growth equation during PINN training is both feasible and beneficial: an ensemble of 100 dual-head networks recovers either local H0 prior exactly, produces indistinguishable fσ8 reconstructions that lie below the ΛCDM+GR curve at essentially all redshifts, and yields Om(z) profiles that are not flat, while the physics weight λ = 0.1 balances data fit
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An underdamped damped-oscillator dark-energy model yields H0 = 70.9 ± 1.1 km/s/Mpc (DESY5) and H0 = 72.0^{+1.4}_{-2.1} km/s/Mpc (Union3), reducing the SH0ES tension to ∼1.5σ, while Bayesian evidence versus ΛCDM is inconclusive; Pantheon+ instead prefers a near-critical solution with H0 = 66.23 ± 0.85 km/s/Mpc.
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An underdamped damped-oscillator dark-energy model yields H0 = 70.9 ± 1.1 km/s/Mpc (DESY5) and H0 = 72.0^{+1.4}_{-2.1} km/s/Mpc (Union3), reducing the SH0ES tension to ∼1.5σ, while Bayesian evidence versus ΛCDM is inconclusive; Pantheon+ instead prefers a near-critical solution with H0 = 66.23 ± 0.85 km/s/Mpc.
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The paper's central discovery claim is that a small out-of-equilibrium axion population — modeled by a BGK collision term whose sign is opposite to the usual relaxation term — produces an axion energy density that deviates from the standard (1+z)³ scaling at redshifts z ≲ 1, effectively acting as a phantom energy component. This modified expansion rate reconciles a high local Hubble constant with
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Supernova peculiar-velocity correlations combined with Planck PR4 CMB data are highly complementary and can measure σ₈, γ and Ω_k simultaneously; the joint fits yield Ω_k ≈ −0.01, excluding flatness at 1.8–2.6σ (depending on SN catalogue) while γ remains consistent with the GR value ≈0.55.
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If physics prior to decoupling is unmodified, the probability of a phantom-crossing late-time dark-energy history is 96.7–98.5 percent and ΛCDM is excluded at approximately 2.5σ (DES-Dovekie) to 3σ (Pantheon+). Early new physics that mainly shifts pre-recombination quantities can alleviate the Hubble tension under the SH0ES calibration, yet it forces extremely large values of ω_m that are in stron
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The central claim is that ΛsCDM improves parameter-space compatibility and softens several late-time tensions relative to ΛCDM, but does not fully reconcile local expansion-rate measurements with CMB- and BAO-calibrated posteriors. In particular, posterior predictive tests show that the observed local Hubble constant lies deep in the tail of the predictive distribution under both models, although
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The central claim is that the horizon entanglement equipartition deficit (HEED) supplies a physical origin for a holographic-style dark energy. Starting from a fractional deficit δ(a)=1−S_ent/S_BH at the apparent horizon, and applying equipartition with the Gibbons–Hawking temperature T=H/(2π) to the missing surface degrees of freedom, the paper derives a bulk density ρ_HEED = (3/8πG) c_e²(a) H²(a
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The central claim is that in the trace-free formulation of unimodular gravity, where the cosmological constant arises as an integration constant, adding a first-order relativistic bulk viscosity whose coefficient scales as ξ = ξ0|Q|^{1/2} with the energy-diffusion function Q yields a closed analytical solution for H(z). With the diffusion function set to Q = νH², the effective vacuum energy acquir
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The central claim is that the second-order modified Friedmann equation for the f(T,T_G) = -T + α√(T² + βT_G) model, with H(0)=H0 and H'(0)=γ treated as free boundary conditions, yields a numerically solved H(z) that fits the combined late-time datasets as well as or better than ΛCDM in terms of χ², while giving H0 from 69.144 to 71.411 km/s/Mpc. This is achieved without a cosmological constant, wi
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In the paper's own terms, the central discovery is that the CPL+Σmν model—dark energy with equation of state w(z)=w0+wa z/(1+z) plus a free summed neutrino mass treated as an effective late-time matter component—reconciles early- and late-universe determinations of H0 better than ΛCDM does. The evolving equation of state systematically moves H0 upward relative to ΛCDM, especially in combinations c
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In the paper's own terms, the central discovery is that the CPL+Σmν model—dark energy with equation of state w(z)=w0+wa z/(1+z) plus a free summed neutrino mass treated as an effective late-time matter component—reconciles early- and late-universe determinations of H0 better than ΛCDM does. The evolving equation of state systematically moves H0 upward relative to ΛCDM, especially in combinations c
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The central claim, stated on the paper's own terms, is that the data force the early-time scaling sector to be inert. For the three models that combine a steep exponential potential with late-time acceleration — scaling-plus-thawing, scaling-plus-Λ, scaling-plus-wCDM — the steepness parameter satisfies λ2 > 30 at 1σ; for the scaling-plus-CPL variant the bound is λ2 > 20. Because an exponential pot
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The central claim is that a phantom-like dark energy built from a 3-form field with a Gaussian potential improves the fit to combined cosmological data over Lambda CDM by shifting H0 upward. The shift is produced by the field climbing its potential around z≈1.7, which changes the late-time expansion history while keeping early-time physics intact. The paper demonstrates the shift through MCMC with
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The central discovery is that a 'special M' realization of extended Proca-Nuevo theory, with an effective dark energy density scaling as H^{2M} and with EPN perturbations set to zero, is preferred over ΛCDM at 1.5σ for CMB+BAO and at 2.4σ for CMB+BAO+PPS. In this decoupled limit the Hubble tension drops from 5.8σ to about 2.3σ (with BAO) or 1.5σ (without BAO). The authors further show that the ful
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The central claim is that the generalized exponential f(R) model, with Lagrangian f(R) = R − 2Λ(1 − exp[−β(R/2Λ)^α]) and three massive neutrinos described by a Fermi–Dirac phase-space density, remains consistent with the joint CC+BAO+CMB+SNe dataset and is very strongly favored over ΛCDM in the AIC comparison when the supernova sample is included. In that full fit the model gives H0 = 70.89 ± 0.19
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On the paper's own terms: in the symmetric teleparallel framework, a nonminimal matter–geometry coupling of the form f2(Q)L_m produces modified Friedmann equations; for the power-law choice f1(Q)=-Q+αQ² and f2(Q)=1+βQ, the model fits all late-time probes with reduced chi-squared near unity and yields H0 in the range 67.7–69.0 km/s/Mpc across four data combinations. The authors interpret this as a
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The central discovery is an anti-correlation between the running index δΛ and the inferred Hubble constant. In the eeΛCDM model, where Λ(z) = Λ0(1+z)^δΛ and G(z) = G0(1+z)^-δG with δΛ and δG treated as independent, the authors find δΛ = -0.410(+0.140,-0.120) and H0 = 71.90 ± 1.00 km/s/Mpc from the combination of CMB, BAO, and local distance-ladder data, easing the H0 tension to 0.8σ. The negative
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The paper's central claim is that the "no-go theorem" excluding post-recombination solutions to the Hubble tension survives even if one grants a fiducial-cosmology-induced, redshift-independent rescaling of all BAO measurements. Modeling the bias by multiplying acoustic angles by λ≈1.06 (the ratio of the local distance-ladder value to the BAO-based value), the authors find that rescaled BAO alone
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The central discovery is that, for the largest joint dataset (P18 + lensing + non-CMB), the inverse power-law index α of the φCDM quintessence potential is constrained to α = 0.055 ± 0.041 (95% upper limit 0.133) in the φCDM model, and α = 0.095 ± 0.056 (95% upper limit 0.196) in the φCDM+AL model. These values are consistent with a cosmological constant (α = 0) at 1.3σ and 1.7σ respectively, mean
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Within a spherically symmetric open FLRW spacetime, the authors couple a nonlinear spinor field minimally to gravity and show that its energy density and pressure obey the generalized Chaplygin gas equation of state, p = −A/ε^α, with ε = λ[A + λ1(1+z)^{3(1+α)}]^{1/(1+α)}. The off-diagonal components of the energy–momentum tensor vanish, imposing consistency conditions on the spinor bilinears. Cons
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On the paper's own terms, the discovery is that Einstein's field equations can be derived rather than postulated in the vacuum-dominated far future: a gravitational version of the Casimir effect, with no plates and no gravitons, yields the Friedmann equations with Newton's constant equal to c^2 R_infinity/(2 M_infinity). The vacuum energy density rho_vac is the only source, with M_infinity c^2 = r
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The central claim is that a crowding-induced bias in HST Cepheid photometry cannot account for the Hubble tension. The key evidence is a three-way comparison inside one galaxy system: HST Cepheids in the crowded spiral, JWST Cepheids in the same spiral, and JWST Cepheids in the tidal companion NGC 3447A, which lacks the old red-giant background that causes crowding. The two JWST components differ
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In the paper's own terms, RCHDE is a holographic dark energy model in which the dark energy density is ρ_DE = (3/κ²)(−αR + λP^{1/3}), with P the cubic curvature invariant formed from cubic contractions of Riemann and Ricci tensors and truncated to first-order derivatives so the field equations stay second order. Feeding this into the first Friedmann equation yields a nonlinear differential equatio
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The paper's central claim is that a minimally modified gravity theory can absorb part of the Hubble tension through the combination of a non-conserved energy-momentum tensor and negative spatial curvature. In the Rastall ΛCDM model, the parameter ε rescales the effective densities of matter, radiation, and the cosmological constant and changes how matter density scales with redshift. The MCMC fits
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The central claim is that the dissipation coefficient $\Gamma$ of warm inflation increases the predicted value of the Hubble parameter enough to match the local measurement of $H_0$, while the tensor-to-scalar ratio $r$ remains consistent with recent CMB missions. This is argued to hold in both the strong ($Q \gg 1$) and weak ($Q \ll 1$) dissipative regimes, across several popular models of warm i
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The claimed discovery is that scalar perturbations in f(T) gravity modify the Poisson and lensing equations, and this modification—combined with a gravitational-constant-dependent supernova luminosity—lets the model bring cosmological observations into better agreement than Lambda-CDM does on the H0 front. On the paper's own terms, the power-law f(T) model, constrained by cosmic chronometers, BBN,
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The central claim is that a spontaneously broken dark gauge symmetry can simultaneously provide dark matter, dark radiation, and the early-time injection of energy needed to relieve the Hubble tension. In the Hot NEDE setup, the dark SU(N) symmetry is broken to SU(N-1) in a supercooled phase transition, creating a thermal bath of self-interacting dark radiation in the epoch between BBN and recombi
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On the paper's own terms, the discovery is that the four-parameter generalized entropy $S_g = \frac{1}{\gamma}\left[\left(1+\frac{\alpha_+}{\beta}S\right)^\beta-\left(1+\frac{\alpha_-}{\beta}S\right)^{-\beta}\right]$ of the apparent horizon produces a late-universe dark-energy sector characterized by an entropic energy density $\rho_g$ and pressure $p_g$. In the late-time limit $GH^2\ll 1$ the dev
Stated claims
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The paper establishes that a vacuum–dark-matter interaction, with the energy transfer unperturbed in the CDM rest frame (δQ = 0), provides a mechanism to lower S8 independently of the early expansion history. When the vacuum decays into CDM, the newly created dark matter carries no density perturbation, diluting the existing contrast: Ωm increases while σ8 decreases, and the net S8 falls. For the combined data set CBS (Planck+BAO+Pantheon+) the posteriors favour m̄ < 0 at 1.8–2.7σ, and the exchange lowers S8 by 0.02–0.08 without raising H0. With the SH0ES calibration (CBSH), the exchange removes the S8 increase of dark radiation (S8 = 0.800 ± 0.016 at H0 = 71.34 ± 0.70 km/s/Mpc) and about a third of that caused by early dark energy (for α = −2). However, the S8 reduction is largest today and amounts to only 1–2% at the redshifts where the KiDS-Legacy lensing kernels peak, and the exchange does not ease the Hubble tension itself.
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Double-plane lenses do not truly break the mass-sheet degeneracy, but they convert it into a measurable quantity. When both planes are modelled with power-law profiles, the freedom to add mass sheets in either plane is absorbed into the model's inferred cosmological scaling factor $\tilde{\eta}$; comparing that $\tilde{\eta}$ with a reference $\eta$ obtained from cosmology and line-of-sight estimates then fixes the combination $\zeta_{12} \equiv \eta\zeta_1 + \zeta_2 - \zeta_1\zeta_2$ of the two planes' mass-sheet components (Eq. 35). Imaging alone does not fix either component individually, but it eliminates large regions of mass-profile space: a positive $\zeta_{12}$, for example, rules out both lenses being 'steepening' relative to a power law. The paper obtains $\zeta_{12} = -0.22^{+0.12}_{-0.13}$ for J1721, $0.052^{+0.022}_{-0.031}$ for J0946, and $-0.191^{+0.126}_{-0.087}$ for AGEL0353, each mildly disfavouring two pure power-law planes. With an auxiliary assumption — a prior on the population scatter of sheets, or a velocity-dispersion measurement in one plane — the individual sheets can be recovered.
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The central claim is that cosmic acceleration is transient in a spatially flat universe whose dark energy follows a specific oscillatory equation of state. The equation of state $w_{\rm de}(N)$ is the solution of $\frac{d^2w_{\rm de}}{dN^2} + f^2(w_{\rm de} - w_{\rm m}) = \Omega_{m0}N^3$ with mean $w_{\rm m} = -1$, where $N = \ln a$ counts e-folds and the source term is normalized to the present matter density parameter. The source term is negligible near the present but dominates at large $|N|$: toward the past it drives the oscillations into the phantom regime $w_{\rm de} < -1$, and toward the future it pushes them into $w_{\rm de} > -1$. Once $w_{\rm de}$ rises above $-1$, the continuity equation forces $\rho_{\rm de}$ to dilute, $H$ decreases asymptotically to zero, and the expansion decelerates permanently, approaching a static state as $a \to \infty$ without contraction. Extrapolated to the future, the BellDE and CPL parametrizations studied alongside show the same replacement of $\Lambda$CDM's eternal de Sitter future, with the sourced-oscillation model extending the accelerating phase by a few e-folds. With Planck and DESI BAO plus one supernova compilation at a time, the model constrains $H_0$ to about $66.1$–$67.8\ \mathrm{km\,s^{-1}\,Mpc^{-1}}$ and $\Omega_m$ to about $0.31$, consistent with the baseline model; all dynamical models sit at lower $H_0$ than $\Lambda$CDM, so none of them relieves the Hubble tension.
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The ZTF SN Ia DR2 dataset, while internally self-consistent, lacks the absolute photometric calibration needed to combine it with external samples such as SH0ES. The missing calibration products include stellar magnitudes tied to a standard system (e.g., Pan-STARRS), updated filter bandpasses, and corrections for detector nonlinearities such as the pocket effect and the brighter-fatter effect. Without these, any cross-survey H0 determination carries an unknown systematic offset that can be as large as 0.1 mag, corresponding to ~3.5 km/s/Mpc on H0. Karchev et al. did not account for this offset, so their result does not constitute a valid cosmological measurement.
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Under a fixed SN Ia framework (Pantheon+ dataset and fitting code), variation in TRGB methodology alone produces H0 values that scatter by 7.38 km/s/Mpc (standard deviation) among submissions, with a tail extending to 99 km/s/Mpc. Two factors dominate: (1) Inclusion of four galaxies (NGC 1309, NGC 3021, NGC 3370, NGC 5584) with low tip contrast and systemically smaller distance moduli—when any of them enters the fit, H0 rises by a median of 6.5 km/s/Mpc; (2) The anchor tip magnitude of NGC 4258, which differs by 0.079 mag (standard deviation) between submissions and shifts all galaxy distances coherntly. Changing smoothing bandwidth, color cuts, and spatial clipping also affects individual distances, but the largest portion of the variance traces back to galaxy selection and anchor measurement. The paper shows that reasonable methodological choices within a single framework can produce substantially different H0 values, and it makes all data and code public so that the differences can be inspected and traced.
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The central claim is that direct determinations of $H_0$ are model-dependent because the apparent magnitude of a standard candle is $m = M + 5\log_{10}(d_L/10\,\mathrm{pc})$, with the luminosity distance $d_L = (1+z)\int_0^z dx/H(x)$ carrying the entire expansion history $H(x)$ and not just the local expansion rate. Within $\Lambda$CDM, varying the one extra parameter $\Omega_M$ moves the inferred $H_0$ only slightly. But in $w_0w_a$CDM, where the dark-energy term depends on both $w_0$ and $w_a$, moving along the degeneracy direction of the DESI ellipse in the $w_0$-$w_a$ plane changes the inferred $H_0$ significantly. The authors emphasize that this claim is not disputed in the paper they are answering, and that their earlier work was only that the background cosmology *can* impact local $H_0$ determinations and *may* be relevant to the Hubble tension, not that it resolves it.
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The paper's positive claim, stated in its conclusions, is that the extra-radiation model with lepton asymmetry can still alleviate the Hubble tension without adopting a helium abundance below the standard BBN prediction: $N_{\rm eff}=3.27\pm0.16$, $\xi=0.017\pm0.011$, $H_0=69.24\pm0.92\,{\rm km\,s^{-1}\,Mpc^{-1}}$, with the Gaussian tension against the SH0ES value $73.17\pm0.86$ falling from $5.74\sigma$ in $\Lambda$CDM to $3.12\sigma$. The mechanism is a two-lever compensation: extra radiation speeds weak freeze-out and raises helium, while a positive $\xi$ acts through the charged-current weak rates that set the neutron-to-proton ratio, lowering helium; the radiation energy added directly by $\xi$ is negligible ($\Delta N^{\xi}_{\rm eff}\simeq4\times10^{-4}$), so the asymmetry works almost purely through BBN weak rates. The complementary result is negative for EDE: the BBN likelihoods tighten the 68% upper limit on the EDE fraction from $0.017$ (without BBN) to $0.012$, because the higher baryon densities favored by EDE lower predicted deuterium, and the small $\xi$ allowed by helium does not compensate deuterium. The paper then shows that a positive light-quark-mass variation during BBN, $\delta_q=0.0072\pm0.0044$, increases deuterium and slightly lowers helium, relaxing the EDE bound to $f_{\rm EDE}<0.019$ and raising $H_0$ to $68.85$ (tension $4.02\sigma$), while leaving the extra-radiation constraints nearly unchanged; it also finds that allowing lepton asymmetry relaxes the 95% upper limit on the summed neutrino mass from $0.0640$ to $0.0777$ eV in the extra-radiation model. The authors state that the quark-mass constraints are conditional on the adopted nuclear response coefficients, which are fixed rather than marginalized.
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Working on the principal Lambert-W branch with $0.5<b<1$, selected through phase-portrait analysis because it approximately reproduces the standard matter-dominated trajectory before reaching a de Sitter attractor, the paper constrains the model with CMB-SPA (Planck, ACT, SPT), DESI DR2 BAO, and PantheonPlus data. The headline results are $b = 0.573^{+0.016}_{-0.060}$ and $H_0 = 70.67^{+0.31}_{-0.35}\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$ (68% CL) for the full combination with the SH0ES calibration, with the torsion equation of state crossing the phantom divide at $z\simeq1.29$. The paper establishes an asymmetry: on CMB data alone the model fits slightly better than $\Lambda$CDM ($\Delta\chi^2 = -2.24$) and reduces the SH0ES tension from $5.13\sigma$ to $2.34\sigma$, yet once BAO and supernova distances are included the combined fit is worse ($\Delta\chi^2 = +7.27$) and the Bayesian evidence weakly favors the standard model. It also notes the model never reduces to $\Lambda$CDM for any parameter value, only to GR without a cosmological constant in the $\beta=0$ limit. The conclusion, stated plainly, is that the extra parameter buys a higher $H_0$ but not the low-redshift flexibility needed to match the full dataset.
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The central discovery is a new measurement of the Hubble constant from a homogeneous, untargeted sample of type Ia supernovae, nearly free of systematic selection biases. Using the volume-limited subset (z < 0.06) of ZTF DR2, together with 42 SH0ES calibrators and a Bayesian hierarchical model, the authors obtain H0 = 71.6 ± 1.5 km/s/Mpc. The uncertainty is dominated by the number of calibrators. The measurement is consistent with the SH0ES value and in tension with Planck, reinforcing the conclusion that the Hubble tension cannot be attributed to inhomogeneous supernova samples or simplified modeling.
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Restricting to a flat FLRW universe with radiation, viscous dark matter, and a cosmological constant, the paper reduces the dynamics to a two-dimensional autonomous system in $(\Omega_r, \Omega_m)$ with $\Omega_\Lambda$ fixed by the Friedmann constraint, and classifies its fixed points. On the radiation branch, the only equilibrium that carries viscous matter would sit at $\Omega_m = 3\Omega_\Pi$ (equivalently $\Pi = \rho_m/3$), which requires a positive viscous pressure; but the Eckart closure $\Pi = -\xi\Theta$ together with the second law $\xi > 0$ makes $\Pi$ negative in an expanding universe. The paper's central claim is that no trajectory can therefore start from a viscous radiation state, so a viable radiation era forces the complete absence of viscosity. At late times the fixed points are the matter point (a saddle whenever $|\Omega_\Pi| \ll 1$), a dissipative de Sitter-like matter point, and the cosmological-constant point (a stable node); for the general class the dissipative point is non-hyperbolic, and the decisive exclusion of it as an admissible attractor is carried by the power-law case study. There, $\Omega_\Pi = -\hat{\xi}_0 \Omega_m^s$ with $s \geq 1$ and $\hat{\xi}_0 \ll 1$ reproduces the $\Lambda$CDM background to better than 1 percent while pushing the dissipative point outside the physical phase space, whereas $s < 1$ creates a past-time boundary $N_{\rm crash}$ beyond which $\Omega_m$ turns negative and $\Omega_\Pi$ becomes complex. The paper concludes that the background is therefore locked to $\Lambda$CDM, making these models unlikely to resolve the $H_0$ tension, and that their remaining physical channel is a scale-dependent dissipative drag that suppresses the growth of sub-horizon matter fluctuations.
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The paper's central claim is that the $r_d$-agnostic strategy — leave the sound horizon free, let BAO constrain $r_d H_0$ and $\Omega_m$, and let CMB and galaxy lensing constrain $\Omega_m h^2$ — reaches useful precision with the next generation of surveys. For fixed $\Sigma m_\nu$, the forecast is $\sigma(H_0)=1.3$ km/s/Mpc with the baseline priors, $0.69$ km/s/Mpc with an informative Gaussian prior on $A_s$, and $1.5$ km/s/Mpc with the least informative prior set; allowing $\Sigma m_\nu$ to vary loosens $H_0$ to roughly $1.3$–$1.8$ km/s/Mpc while bounding the neutrino sum at 95% CL near $0.36$ eV. The paper also predicts a 25–30% reduction in $\sigma(H_0)$ relative to the current-data analysis it extends, with the biggest gain occurring when $\Sigma m_\nu$ is free. The boundary of the claim is set by its validation tests: mock data from a modified-recombination model are recovered without bias under all three priors, while mock data from an early-dark-energy model are not, with the pipeline returning $H_0\simeq 69.8\pm 1.0$ km/s/Mpc against an injected value of $71.45$ km/s/Mpc.
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Applying host-galaxy redshift corrections for peculiar velocities to the low-redshift calibrator supernovae brings the second-rung intercept of the magnitude–redshift relation into closer agreement with the third-rung intercept, lowering the significance of the discrepancy from 6.8σ to 3.9σ in the forward check and from 7.3σ to 4.3σ in the backward check. The recovered Hubble constant shifts from $74.30^{+1.18}_{-1.20}$ to $71.37^{+1.23}_{-1.18}$ km s$^{-1}$Mpc$^{-1}$ in the forward analysis and from $60.83^{+0.98}_{-0.97}$ to $63.25^{+0.95}_{-0.93}$ km s$^{-1}$Mpc$^{-1}$ in the backward analysis, both moving toward the Planck-CMB input. The paper concludes that roughly half of the reported intercept tension is a local-velocity artifact, but a residual roughly 4σ offset persists within the adopted framework.
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The paper shows that a phenomenological parametrization unifying early- and late-time expansion history, while providing a better statistical fit to current cosmological data than ΛCDM, cannot significantly raise the Hubble constant when the early-time background is restricted to an analytic radiation–matter transition. The central discovery is that even with additional freedom in the late-time expansion (via parameters η1, η2, η3), the sound horizon at last scattering remains nearly unchanged, and the Hubble constant inferred from CMB+BAO+SNe data (with or without the SH0ES prior) stays far below the local measurement. This implies that the Hubble tension cannot be solved by merely adjusting the matter-like density or late-time dynamics; an additional localized feature in the pre-recombination expansion history, such as that provided by early dark energy, is required.
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The authors' central claim is that the self-interacting potential $V(\phi) = \tfrac12 m^2\phi^2 + \tfrac{\lambda}{4}\phi^4$ with $\lambda > 0$ produces, from one field, the two complementary effects that earlier work had to build from separate components: the quartic-dominated oscillatory phase behaves as radiation with $\langle w_\phi\rangle = 1/3$, increasing the pre-recombination expansion rate and reducing the comoving sound horizon, while the subsequent quadratic phase with $\langle w_\phi\rangle = 0$ turns the same field into dark matter whose scale-dependent effective pressure suppresses late-time clustering. Evolving the background and linear perturbations in CLASS for a mixed CDM+ULDM dark sector, with the microscopic mass $m = 10^{-22}$ eV and the quartic-to-quadratic scale $\tilde m \equiv m/\lambda^{1/4} \simeq 1$ eV, the paper fixes the acoustic angular scale $\theta_*$ to its $\Lambda$CDM reference value and finds that increasing the present-day scalar fraction $f_{\rm UDM}$ from 0.05 to 0.20 raises $H_0$ from 67.9700 to 69.1022 km s$^{-1}$ Mpc$^{-1}$, reduces $r_s(z_{\rm rec})$ from 144.4907 to 144.0259 Mpc, and lowers $\sigma_8$ from 0.780514 to 0.619318. The matter power spectrum is suppressed scale-dependently — at $k = 0.1$ Mpc$^{-1}$ the ratio $P/P_{\Lambda\mathrm{CDM}}$ falls to 0.532 and at $k = 1$ Mpc$^{-1}$ to 0.289 for $f_{\rm UDM} = 0.20$ — and the CMB temperature residual stays smooth while reaching about 8.9%. Stated on the paper's own terms, the main result is the numerical realization of a single self-interacting-ULDM mechanism that links an early reduction of the sound horizon to a later suppression of structure growth, shown to survive a stress-energy-consistent treatment of linear perturbations.
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The core discovery is that a linear differential equation of third order arises from the holographic density ansatz $\rho_H = 3M_p^2 [\alpha H^2 + \beta \dot{H} + \gamma \ddot{H}/H + \eta (1/H) d/dt(\ddot{H}/H)]$ when recast in the variable $x=\ln a$ with $E=H^2$. The conditions $A_m=A_r=1$ fix two parameters, leaving the solution $H^2 = H_0^2 (\Omega_{m0}a^{-3}+\Omega_{r0}a^{-4}+\sum C_i a^{\lambda_i})$, where the characteristic exponents $\lambda_i$ satisfy $\eta\lambda^3+\gamma\lambda^2+\beta\lambda+2(1-\alpha)=0$. Two roots can fall between $\lambda=-3$ (matter) and $\lambda=-4$ (radiation), enhancing expansion around recombination, while a slightly positive root ($0.15\lesssim\lambda_1\lesssim0.30$) acts as a phantom component that raises the late-time $H_0$ when the acoustic scale is fixed, albeit strongly limited by BAO distances.
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The central claim is that future TianQin standard siren measurements will leave the current preference for dynamical dark energy intact regardless of which background cosmology produced the data. After fitting $\Lambda$CDM and the four-bin wbin model to the DESI DR2+CMB+DESY5 combination, the authors feed the mean parameters into the same massive-black-hole-binary simulation to make TQSS1 ($\Lambda$CDM-based) and TQSS2 (wbin-based). The catalogs' luminosity distances differ by at most $1.48\%$, with the low-redshift part tracing the input Hubble constant and the $1.02\%$ gap at $z\simeq0.85$ attributed to the genuine equation-of-state difference; this smallness is presented as evidence that the catalogs are comparable probes. Yet the two catalogs push in opposite directions when combined with the real data: TQSS1 lowers the dynamical-dark-energy significance from $3.0\sigma$ to $2.3\sigma$, while TQSS2 raises it to $3.8\sigma$. The paper further reports that switching from light (pop III) to heavy (Q3nod) black hole seeds changes only the number of simulated events and the tightness of contours, not the conclusions, and it acknowledges that the mock catalogs cannot independently assess the Hubble tension because $H_0$ is an input.
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The core discovery is that the inverse distance ladder, when confined to the single-instrument, homogeneous DES-Dovekie SNIa catalogue, does not rule out a late-time resolution of the Hubble tension. The widely reported IDL-based disfavor of late-time solutions depends critically on including legacy SNIa from multiple surveys, which the paper shows are offset by ~0.065 mag relative to the DES sample. This offset, if due to photometric recalibration systematics, would resolve the tension between IDL and local H0 measurements. The paper further shows that a phenomenological late-time enhancement to H(z) (an exponential bump with amplitude A ≈ 5–8 km/s/Mpc and scale z1 ≲ 0.1) is consistent with the data when the legacy SNIa are excluded or recalibrated, and is strongly preferred when local H0 anchors are included.
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The core claim is that time-delay cosmography has come of age. By combining precise time delays with high-quality lens models, stellar kinmatics, and line-of-sight corrections, the TDCOSMO collaboration measured H0 to 3% precision using 11 quasar lenses. This method is independent of the distance ladder and CMB, and its systematic errors are estimated to be below 1% per lens for galaxy-scale deflectors. The review also reports a tentative detection of dark matter self-interaction via the excess density of subhalos, preferring SIDM over CDM. These results position strong lensing as a key player in resolving the Hubble tension and constraining dark matter models.
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The claim is stated on the paper's own terms in Section 3.1: the mean intergalactic dispersion measure responds as $\delta\ln\langle{\rm DM}_{\rm IGM}\rangle \simeq \delta\ln H_0 + \delta\ln\Omega_{\rm b}$, so FRB data alone carve out a broad band of roughly constant $\Omega_{\rm b} H_0$ in the $H_0$--$\Omega_{\rm b}$ plane. DESI DR2 BAO, taken without any external calibration of the drag-epoch sound horizon $r_d$, constrain the combination $H_0 r_d$ and produce a band that is nearly transverse to the FRB band. Their intersection is compact: $H_0 = 71.4^{+2.2}_{-2.5}$ km s$^{-1}$ Mpc$^{-1}$, $\Omega_{\rm b} = 0.0503^{+0.0025}_{-0.0021}$, and $r_d = 142.4 \pm 4.8$ Mpc (Equation 20, Table 2). The inferred $H_0$ lies between the Planck value $67.36 \pm 0.54$ and the SH0ES distance-ladder value $73.04 \pm 1.04$ km s$^{-1}$ Mpc$^{-1}$, consistent with both at 1.7$\sigma$ and 0.6$\sigma$, and $\Omega_{\rm b}$ agrees with the joint BBN+CMB determination at better than 1$\sigma$. The paper also reports that the $H_0$--$\Omega_{\rm b}$ result is barely changed when supernova samples are added, whereas the dark-energy parameters $w_0$, $w_a$ remain dominated by BAO and supernovae.
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The central claim is Eq. (20): under particle number conservation, the metric variation of the standard perfect-fluid energy-momentum tensor collapses to the $L_m$-independent form $\Theta_{\sigma\gamma}=\tfrac12\rho(g_{\sigma\gamma}-u_\sigma u_\gamma)\frac{\partial(\epsilon-3P)}{\partial\rho}-T_{\sigma\gamma}$, obtained by varying $T_{\mu\nu}$ directly rather than through a matter Lagrangian. The author states this differs significantly from prior values, notably the diagonal components $\Theta_1^1=\epsilon+2P$ and $\epsilon=-\tfrac12(5\rho+3P)$ found in earlier studies. If correct, a universe containing only dust, radiation, and a cosmological constant obeys $\nabla_\mu T^{\mu\nu}=0$ identically for any $f(R,T)$, a result the paper calls one of its main findings. The same tensor, inserted into the stellar interior, yields a modified TOV equation and a specific model consistent with neutron-star maximum masses of about $2.2$-$2.35\,M_\odot$.
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The central claim is that the extended SCM — the classical velocity-plus-color correction augmented by a linear term in the H$\alpha$ absorption-to-emission ratio — standardizes Type II-P supernovae far better than the classical method, and that a hierarchical Bayesian fit recovers the standardization coefficients more faithfully than the traditional non-hierarchical approach. In support, the authors reduce the Hubble-flow scatter from 0.28 mag (comparable to previous work) to 0.18 mag, and find $H_0 = 70.6^{+4.5}_{-4.3}$ km s$^{-1}$ Mpc$^{-1}$, versus $73.0^{+6.9}_{-6.1}$ without the $a/e$ term. The $a/e$ correction improves standardization most around 30–40 days after explosion and widens the usable standardization phase window to roughly 30–50 days, which is why the analysis standardizes at 30 days with 18 SNe rather than at the literature's 43–50 days.
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The central claim, on the paper's own terms, is that LISA bright sirens offer sharply asymmetric discriminating power as a tiebreaker in the Hubble tension. A catalogue generated in a Pantheon+SH0ES universe — $H_0\approx 73$ km/s/Mpc, the Cepheid-calibrated end — is inconsistent with every real-data background the authors test, at significance far beyond 5$\sigma$ for the 768 simulated events, still above 5$\sigma$ at 50 bright sirens, and at 3–5$\sigma$ by Fisher estimate for the 10–20 counterpart events expected from recent population models. The exclusion is carried by the two-dimensional offset running across the $H_0$–$\Omega_m$ degeneracy, so the one-dimensional marginals understate it badly. By contrast, the Planck-2018 and Union3 fiducials, separated by only 0.24 km/s/Mpc in $H_0$, differ in their tension from a common background (2.1$\sigma$ versus 3.3$\sigma$) by less than the $\pm 0.4\sigma$ scatter between noise realisations and cannot be separated by enlarging the catalogue, which tightens both equally. The paper argues this asymmetry — not any ranking of the three — is the result that carries forward. It also shows the waveform supplies no prior of its own: catalogues built at $H_0$ from 35 to 115 km/s/Mpc are recovered with essentially the same fractional precision, so rejecting an implausible expansion history is done entirely by the electromagnetic comparison.
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Once cosmic unevenness is promoted from a nuisance to a dynamical component, both the dark-energy density parameter and the expansion rate become functions of redshift. The central derived numbers are Ωvol = 2/3 for the early, homogeneous universe; ΩΛ,het(z) rising from 0.679 to 0.735±0.010 today; H0,het(z) rising from the Planck value 66.88 toward roughly 73.6 km/s/Mpc; and an integrated cosmic age of 13.521 Gyr, which is 0.306 Gyr shorter than the homogeneous age, stated as a global time dilation. Because the redshift dependence emerges from the growth of heterogeneity — entering through σ8 — and uses no newly fitted parameter, the author presents the mechanism as resolving the Hubble tension and as predicting, rather than accommodating, the time-evolving dark energy favored by recent combined analyses.
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The paper argues that a two-rung TRGB ladder — tip magnitudes, geometric anchors, and host redshifts, with no supernova rung — is limited at the present sample depth by the reconstruction of the local density and peculiar-velocity field, not by the TRGB calibration. Across the 80 Manticore-Local realizations of the local Universe, the per-field median H0 scatters by 5.2 km/s/Mpc, and this scatter is what caps the precision. The evidence-weighted constraint H0 = 72.3 ± 2.6 km/s/Mpc is set by a single dominant realization, with an effective sample size of Neff = 1.00 out of 80, so it is sensitive to the finite sampling of the reconstruction posterior; the equal-weight stack of H0 = 68.4 ± 5.9 km/s/Mpc retains the field-to-field scatter and brackets the reconstruction sensitivity. Because at fixed realization the redshift-likelihood choice, density-smoothing scale, and sky-exposure modeling each move H0 by less than 1 km/s/Mpc, while the field-to-field scatter is 5.2 km/s/Mpc, the authors conclude that this ladder cannot yet distinguish between the competing Hubble-constant values and that the gains lie in extending the TRGB sample depth or improving the local reconstruction.
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The central claim is that the Noether symmetry of the point-like Lagrangian (3.5) selects the multiplicative power-law $f(Q,B)=f_0(-Q)^\alpha B^\beta$ together with a conserved Noether charge, and that the resulting exact solution $a(t)=a_0(t-t_0)^{2(\alpha+\beta)/3}$ produces late-time acceleration when $\alpha+\beta>3/2$. Integrated numerically and fit to CC, Pantheon+, SH0ES, and DESI DR2 data, the reconstructed Hubble evolution tracks the $\Lambda$CDM background, with the CC+DESI DR2 combination giving $\Delta\mathrm{AIC}=1.41$, $\Delta\mathrm{BIC}=4.93$, and $H_0=67.5^{+1.4}_{-1.6}$ km/s/Mpc, while the SN-inclusive combinations yield higher values reaching $74.4^{+3.8}_{-4.1}$ km/s/Mpc. The paper reads the dataset-dependent span of $H_0$ and the near-parity of the fit statistics as demonstrating that the power-law $f(Q,B)$ model is a viable alternative to the standard cosmological paradigm.
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The central claim is that cosmic acceleration can arise from energy non-conservation in a trace-free gravitational theory without a gravitating vacuum energy, but only if the violation is confined to the dark matter sector. The universal model is intrinsically rigid: raising the matter density improves the intermediate-redshift normalization of H(z) preferred by BAO, yet also raises q0 = −1 + 3Ωm/2 and weakens the present acceleration, so the two-probe fit fails badly (Δχ² ≃ 51, lnB ≃ −26 against ΛCDM). Restricting non-conservation to CDM keeps baryonic, photon, and neutrino observables standard at background level, permitting a self-contained analysis in which the one-parameter ξCDM model beats ΛCDM by Δχ² = −4.85 with lnB = 2.77 for the supernova-plus-DESI-BAO combination. The paper also reports that ξCDM does not resolve the Hubble tension: with BBN or CMB anchors the sound horizon grows and H0 falls, worsening the discrepancy with the distance ladder.
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From five megamaser-hosting galaxies, the authors obtain a purely geometric, ladder-independent constraint on the Hubble constant of H0 = 71.6 ± 3.7 km/s/Mpc (statistical) using a fiducial configuration that includes a redshift-based selection threshold, the non-linear Manticore-Local peculiar-velocity reconstruction, and a uniform-in-volume distance prior. This result resolves none of the Hubble tension but places the megamaser measurement in the intermediate regime, inconsistent with neither Planck nor SH0ES at the current 5% precision. The paper further demonstrates that the MCP's internal reanalysis of maser spot measurements (affecting mainly NGC 6264 and NGC 6323) raises H0 by 1.8–2.1 km/s/Mpc relative to the published catalogues, and that the non-linear peculiar-velocity correction lowers it by 1.6–2.1 km/s/Mpc relative to ignoring peculiar motions.
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The central discovery is that the McVittie metric implies a systematic but extremely small bias on the Hubble constant inferred from supernovae. The bias is proportional to the parameter μ = H_dS m_H, which for Sagittarius A* is about 4.6 × $10^{{-17}}$. The fractional distance deviation Δd_L/d_L is on the order of $10^{{-15}}$%, ruling out the possibility that a local mass like the Milky Way's black hole could resolve the Hubble tension. To achieve an 8.4% shift, an unrealistic effective mass of 3.5 × $10^{{19}}$ solar masses (μ ~ 4 × $10^{{-4}}$) would be required, far exceeding any observed bound structure.
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The paper's central claim is that a curvature-coupled dark energy model specified by the shifted quartic coupling $f(\varphi)=\alpha(\varphi^2-\varphi_{\rm today}^2)^2$ and the inverse power-law potential $V(\varphi)=\Lambda\varphi^{-\sigma}$ can simultaneously satisfy local gravity constraints at the present epoch, modify the pre-recombination expansion history to shift the acoustic scale in a direction that favours a higher Hubble constant, produce a smooth effective crossing of the phantom divide at low redshift without instabilities, and generate scale-dependent changes in the effective Newtonian response, gravitational slip, and metric potentials that translate into characteristic suppressed-then-enhanced weak-lensing power spectra and strongly amplified late-time Integrated Sachs–Wolfe signals.
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The central discovery is that the LBT measurement of the primordial helium fraction, when used as an empirical calibration in CMB analysis, produces cosmological constraints (on parameters such as the Hubble constant, matter density, and inflationary parameters) that are equally tight as those derived under the assumption of standard BBN. This means that one can test or bypass BBN physics without losing constraining power on cosmology, provided the helium measurement has at most a modest improvement in precision over the current LBT data.
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The authors demonstrate numerically that a set of four axion fields with specified parameters yields a specific expansion history: the BBN axion peaks at z~$10^{9}$ with Ω~0.0099, the two early dark energy fields peak at z~7900 and z~2400 with individual fractions 8.6% and 7.8% (combined 9.7%), and the late-time field gives Ω_DE,0=0.685. The three transient fields leave a total residual fraction of 6.0×$10^{{-7}}$ today. This is achieved without fine-tuning the initial conditions beyond a common hilltop offset δ=0.30 for the transients and demonstrating sensitivity to this parameter.
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The paper constrains the damped harmonic oscillator (DHO) equation of state, in which the dark-energy equation of state $w_{\rm de}$ obeys $d^2 w_{\rm de}/dN^2 = -f^2(w_{\rm de}-w_{\rm m}) + b\, dw_{\rm de}/dN$ with $N=\ln a$, against Planck 2018 plus DESI DR2 BAO plus each of Pantheon+, DES-Dovekie, and Union3. Its claim is that the same model, with a single equilibrium value $w_{\rm m}=-1$, lands in qualitatively different dynamical regimes depending on the supernova compilation: underdamped oscillating solutions for DES-Dovekie and Union3, with present-day $w_0 \simeq -3.01$ and $-3.16$ and $H_0 = 69.08$ and $70.67$ km/s/Mpc, and an overdamped solution for Pantheon+ (with sound speed $c_s^2=10^{-5}$, labeled PPM), with $w_0=-0.521$ and $H_0 = 67.53$ km/s/Mpc. In all cases the model converges to $\Lambda$CDM at higher redshift and departs only below $z\sim0.6$. The paper further claims that the higher $H_0$ values are a geometric degeneracy with the matter density rather than an easing of the Hubble tension, since the sound horizon stays near $r_d\sim147$ Mpc, and that model comparison consistently favors CPL over DHO, with logarithmic Bayes factors $\Delta\ln B_{\rm DHO,CPL}$ between $-1.41$ and $-4.49$.
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The paper estabishes that the cluster mass function, measured from 4196 eRASS1 clusters at z<0.45 with weak lemsing mass calibrtion, can constrain EDE paramters. While eRASS1 alone gives only an upper limit f_EDE<0.3, a full Bayesian joint analysis with external CMB, lensing and BAO datasets yields f_EDE = 0.$10^{{+0.04}}$_{-0.03}, log10(z_c)=3.53±0.09, and H₀=71.4±1.4 km $s^{{-1}}$ $Mpc^{{-1}}$. This result is obtained without any distnce-lawer calibration, making it an independent test that favors an EDE soltion to the Hubble tension.
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The paper reports that, across all data combinations (CMB-SPA, DESI DR2 BAO, and four different supernova samples), the conformally interacting dark energy (CIDE) and its dynamical cousin wCIDE yield as good as or better χ² fits than ΛCDM. The best-fit coupling parameter m is consistently positive at 95% confidence, indicating an energy flow from dark matter to dark energy. The wCIDE model, with a quintessence-like equation of state (w > -1), brings the Hubble constant inferred from combined early/late data into closer agreement with the SH0ES local measurement, reducing the tension from ~5σ to below 1.7σ in some dataset combinations. The S8 tension with weak-lensing surveys stays below 2σ. The perturbative analysis (transfer functions, matter power spectrum, growth rate) shows that the model enhances structure on small scales and suppresses it on large scales relative to ΛCDM, which is consistent with the observed growth data.
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The central discovery is that while current cosmological data show a statistically significant preference (at >95% CL) for a transfer of energy from dark energy to dark matter in both emergent DE models, this interaction does not improve the overall fit enough to overcome the penalty of additional parameters. As a result, both ΛCDM and the w0waCDM parametrization remain preferred in terms of Bayesian evidence. Furthermore, the combination of CMB with supernova data yields values of H0 consistent with Planck ΛCDM, eliminating the CMB-only improvement in Hubble tension, and leads to low S8 values that may conflict with weak-lensing measurements.
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The central claim is that the power-law f(Q) gravity model, when fitted via the phenomenological EoS parametrization ω(z) = -1/(1+γ(1+z)^n, provides an observationally viable and competitive description of late-time cosmic acceleration. Using combined datasets (CC + DESI DR2 BAO + Pantheon+/DES-SN5YR/Union3), the model obtains H0 ≈ 67–68 km/s/Mpc, consistent with Planck 2018, and produces a present-day effective EoS ω0 between –0.68 and –0.77 (quintessence-like), a deceleration parameter q0 ≈ –0.4, and a transition redshift z_t ≈ 0.68–0.74. Statistically, the model yields lower χ²_min values than flat ΛCDM and is preferred by AIC (ΔAIC from –1.8 to –7.9), whereas BIC (ΔBIC from +0.2 to +9.1) favors ΛCDM for the two larger datasets, indicating that the improved fit does not always compensate for the extra parameters. The Statefinder and Om(z) diagnostics support quintessence-like behavior and approach the ΛCDM fixed point in the far future. The authors conclude that the power-law f(Q) model is a viable and competitive alternative to ΛCDM for describing late-time cosmic acceleration.
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The authors claim that the Hubble tension can be resolved (or significantly alleviated) when using generalized PAge parameterizations that allow the expansion history to differ from ΛCDM in the mid-time epoch (redshifts between the CMB last-scattering surface and the onset of late-time acceleration). The original PAge parameterization could not incorporate CMB data and had flaws that made it unsuitable for drawing no-go conclusions about late-time modifications; the corrected GPAge versions overcome these issues. The data (including CMB, BAO, SNe Ia, and local H0 measurements) overwhelmingly favor GPAge models over ΛCDM by all common information criteria, and these preferred models have expansion histories that differ substantially from ΛCDM at intermediate redshifts, pointing to new mid-time physics as the key.
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Within flat ΛCDM with a uniform prior on Ωm and the internal mass-sheet parameter held at λ_int = 1, the three JWST/NIRCam models yield H0 = 73.4+3.4−4.4 km/s/Mpc for WFI2033, 74.2±4.2 km/s/Mpc for HE0435, and 71.8+9.2−7.0 km/s/Mpc for PG1115, combining to H0 = 73.5+2.7−2.8 km/s/Mpc. This matches the HST-based combination of 73.6±2.6 but with markedly better mutual agreement among the systems, and the PG1115 and HE0435 analyses were performed blind. The paper further shows that the WFI2033 shift relative to HST-based modeling is driven by the JWST data pinning down a satellite near the deflector and by the earlier analysis' flexible image positions, not by cosmology. Each quoted value carries a factor of λ_int, so the numbers are conditional on the power-law mass-profile assumption until a free-λ_int hierarchical analysis of the full sample is completed.
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Using only the 32 cosmic-chronometer measurements, the paper finds a systematic and monotonic ordering: as kernel smoothness increases from Matérn 3/2 through 5/2, 7/2, 9/2 to the Squared Exponential kernel, the reconstructed Hubble constant decreases monotonically, $H_0 = 70.1 \pm 6.6 \to 69.3 \pm 5.6 \to 68.8 \pm 5.2 \to 68.3 \pm 5.0 \to 67.2 \pm 4.8$ km s$^{-1}$ Mpc$^{-1}$, with uncertainties shrinking accordingly. The same smoothness hierarchy is visible in the first derivative: the slope $dH/dz$ at $z=0$ increases monotonically from $38.1 \pm 31.4$ to $47.2 \pm 16.2$ km s$^{-1}$ Mpc$^{-1}$, and the paper reads the anti-correlation between $H'(0)$ and $H_0$ as the mechanism linking differentiability to the lower $H_0$. The goodness-of-fit statistic $\chi^2$ follows the same ordering, $\chi^2_{3/2} < \chi^2_{5/2} < \chi^2_{7/2} < \chi^2_{9/2} < \chi^2_{\mathrm{SE}}$, both for the chronometers alone and after adding DESI DR2 BAO data, but the paper is explicit that this is descriptive: the spread in maximized log marginal likelihood ($\Delta\mathrm{LML} < 0.12$) and in leave-one-out scores is far too small for any kernel to be statistically preferred. The conclusion is that kernel smoothness acts as an effective prior that reshapes the reconstructed expansion history, not as a fingerprint of the true one.
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For the inverse power-law EDE model with index n=10, fitting CMB+BAO+SN+H0DN data gives a posterior mean H₀ = 70.20⁺⁰·⁶⁰₋₀·₄₇ km/s/Mpc (best-fit 70.56), compared to ΛCDM’s 68.62. The EDE fraction peaks at f_EDE ≈ 0.079 at redshift z_c ≈ 3.5, and the model is preferred over ΛCDM with ΔAIC = −11.1. The Hubble tension, measured by Q_DMAP, drops from 6.25σ (ΛCDM) to 4.79σ (EDE). The model also predicts an increased S₈, worsening the S₈ tension, and leaves detectable imprints in CMB and matter power spectra that future data can test.
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Within the inverse-power-law ("Peebles-Ratra") potential $V\propto\phi^{-\beta}$ and power-law mass $m\propto\phi^\alpha$, the coupled dark sector reproduces the $w_0$-$w_a$ expansion history preferred by CMB+BAO+SN data. The best-fit CDS-PR-$\alpha$ model has $\phi_i\simeq6.9\,M_{\rm Pl}$, $\alpha\simeq0.3$ and $\beta\simeq5.5$, and its $\Delta\chi^2_{\rm MAP}=-7.8$ is comparable to $w_0w_a$CDM's $-7.6$; in the geometric-only combination (BAO+SN+BBN+$\theta_*$) the same model reproduces the $w_0w_a$ best fit with $\alpha\simeq0.1$. The field's canonical equation of state satisfies $|w_\phi|\le1$, and the crossing in the inferred $w(z)$ arises only because the dark matter density deviates from $a^{-3}$ scaling as the dark matter mass varies, so the total dark-sector density is fit as if it were a passively scaling dark matter plus a $w_0$-$w_a$ dark energy. The constant-potential versions of the model alleviate the Hubble tension but cannot reproduce the geometric-only dynamical dark energy signal, showing that the inverse-power-law potential is essential to the result.
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A multi-axion-multi-instanton system can in principle provide both the required aligned light direction (with an effective decay constant f_eff of order 1e18 GeV, about 100 times the heterotic scale) and a higher-order effective potential (V ~ (1 - cos theta)^n, n > 1) that makes the 1e-28 eV contribution transient, thereby reducing the sound horizon enough to address the Hubble tension, while a 1e-22 eV mode collapses to seed supermassive black holes. The paper estimates that addressing the Hubble tension requires a sound-horizon-weighted axion fraction of order 0.1, corresponding to f_eff ~ 1.1e18 GeV.
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On the paper's own terms, the central discovery is a negative result turned positive: an early-universe modification cannot remove the DESI late-time signal. In the full-data fit of the EDE-CPL model (CMB distance priors, DESI DR2 BAO, Pantheon+ supernovae with the SH0ES subsample), the CPL parameters are constrained to $w_0 = -0.85 \pm 0.06$ and $w_a = -0.56 \pm 0.23$, a clear departure from the cosmological constant that the same analysis finds when DESI is excluded. The EDE sector in this fit ($f_{\rm EDE} \approx 0.14$, $z_c \approx 3.55$, $w_f \approx 0.71$) takes its expected values for resolving the Hubble tension, yet the late-time dynamics persists, favoring a transition from phantom ($w < -1$) to quintessence ($w > -1$) behavior. Comparing EDE-CPL with EDE-$\Lambda$CDM gives $\Delta\mathrm{AIC} \approx -3.1$ in favor of adding the CPL parameters, a moderate but consistent preference. The conclusion stated by the paper is that the DESI BAO preference for dynamical dark energy is robust and cannot be absorbed by modifying the physics of the early Universe.
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Within the EDENS suite, two gravity-only N-body simulations of $(1200\,\mathrm{Mpc})^3$ each with $2048^3$ particles and identical initial phases, the EDE cosmology yields a halo mass function roughly 12% higher at $z=0$ and 18% higher at $z=1$ than the $\Lambda$CDM baseline, with the gap growing toward higher redshift. The nonlinear matter power spectra differ by more than 5% at some scales around $k\sim0.1\,\mathrm{Mpc}^{-1}$, where the BAO wiggles sit, and the EDE model forms about 21% more luminous red galaxies at $z=0.5$ when populated with a standard halo occupation distribution. The galaxy two-point correlation function is lower for EDE on small scales, with its BAO peak shifted to slightly smaller separations, while the galaxy bias stays close to $b\sim1.7$ in both models. The concentration–mass relation, by contrast, is too similar between the two cosmologies to serve as a distinguishing probe.
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This paper claims that the slope of a dark energy model's trajectory in the plane spanned by the equation of state $w$ and the sound speed $c_s^2$, evaluated today, controls how background and perturbation observables move together. Concretely, combining the distance-measurement degeneracy $\delta H_0 = (H_0/f)(\partial f/\partial w)\,\delta w$ with the linear response $\delta \ln \sigma_8 \simeq A\delta w + B\delta c_s^2$ and the flow relation $\delta c_s^2 \simeq F\delta w$ gives the central result $\delta \ln \sigma_8 \simeq ((A+BF)/C)\,\delta H_0$, so the present-day flow value $F_0$ determines how a shift in $H_0$ propagates into $\sigma_8$. The paper also claims that the $w-c_s^2$ plane and the derived hierarchy $F$ and $K = d^2 c_s^2/dw^2$ separate canonical quintessence, Chaplygin gas, and noncanonical scalar field models that appear degenerate in $w(a)$ alone.
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On the paper's own terms, the central discovery is a separation between statistical fit and dynamical behavior. All four emergent models, whose dark-energy or curvature terms switch on through a hyperbolic-tangent-type function, fit the low-redshift expansion data well enough to remain viable alternatives to $\Omega_k$-\Lambda CDM, with PEDE named as the best candidate by AIC and BIC in the abstract. But only the variable-curvature model predicts $q(z)>0$ near $z=0$, a return toward deceleration, matching the tendency in the DESI dark-energy reconstruction; it also gives an older universe and curvature values closer to Planck. The same information criteria, once high-redshift data are included, favor the simpler $\Omega_k$-\Lambda CDM, meaning the statistical ranking and the dynamical fingerprint do not point to the same model.
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Using 189 ultra-compact massive galaxies selected by a high degree of relicness in $0.07\le z\le0.22$, the paper finds $\frac{dD_{n}4000}{dz}=-0.33\pm0.19\,[\mathrm{fit}]\,\pm0.07\,[\mathrm{bin}]$. Combined with the MILES single-stellar-population calibration $A\equiv \frac{dD_{n}4000}{dt}\simeq0.033$ Gyr$^{-1}$ (with $A$ depending on metallicity $Z$ and $[\alpha/\mathrm{Fe}]$), this gives the first relic-based Hubble parameter, $H(z=0.15)=85.0\pm51.5\,[\mathrm{stat}]\,^{+10.2}_{-8.9}\,[\mathrm{sys}]$ km/s/Mpc. The central discovery is not the precision of this number but the structure of its error budget: because the relic sample's metallicities sit near the turnover of the $A(Z)$ relation, metallicity contributes at most 1.2 percent, and because the sample is old and homogeneous, star-formation-history systematics are assumed subdominant. The dominant stellar-population systematic is $\alpha$-element enhancement, contributing roughly 9 percent and raising the total systematic from 8.7 to 13 percent when propagated.
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The central discovery is that the level of evidence for dynamical dark energy, measured by fitting the CPL parametrization $w(a)=w_0+w_a(1-a)$ to BAO and uncalibrated supernova data, is not a single number but a field over the early-universe parameters ($H_0 r_d,\Omega_m$). Only the product $H_0 r_d$ and the expansion shape $E(z)$ are accessible to these late-time probes, so the same data can support 'cosmological constant' or 'dynamical dark energy' depending on where the early universe places the model. The CMB angular scale provides an almost model-independent ridge in this plane, and the minimum of the dynamical-dark-energy preference, the 'nexus,' sits on that ridge without having used CMB data. Early-universe solutions to the Hubble tension, which move the joint fit to higher $H_0 r_d$ and lower $\Omega_m$, push the fit toward that nexus and reduce the significance from about 2.5σ to 1.3σ, making the apparent preference depend on the assumed early cosmology. A fourth-order Chebyshev reconstruction of the dark energy density confirms the same weakening near the nexus.
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The central claim is that 17 recently discovered lensed quasars can be carried through one largely automated modeling path to deliver predicted time delays, Fermat potential differences, and a quantified cosmography-readiness ranking. Using a power-law-plus-external-shear mass model with joint S\'ersic light profiles and a shapelet source basis, the pipeline converges for every system, including rare triply imaged configurations and dual-lens systems. Assuming a fiducial cosmology ($H_0 = 70\ \mathrm{km\,s^{-1}\,Mpc^{-1}}$, $\Omega_{m,0} = 0.3$) and a fiducial 2-day monitoring error, the combined time-delay distance uncertainties place six systems in the excellent tier (J0316-4106, J0719+5255, SDSSJ1640+1932, GRALJ1651-0417, DECALSJ2157-4201, DESIJ2321-0330) and five in the good tier (J0457-7820, J0608+4229, J0803+3908, J0833+2612, DELVEJ1258-0319). The paper is explicit that the mass-sheet degeneracy is not broken here and that the quoted uncertainties are conditional on the single power-law assumption for the mass profile.
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The central discovery is that previous megamaser-based estimates of $H_0$ were biased upward by peculiar motions, not by the megamaser distance measurements themselves. Using the M25 velocity reconstruction to correct the six redshifts, the maximum-likelihood $H_0$ becomes $68.7\pm2$ km s$^{-1}$ Mpc$^{-1}$ when the velocity uncertainty $\sigma_v$ is treated as a fitted parameter and marginalized; the probability that $H_0$ is as large as the distance-ladder value of 73.5 km s$^{-1}$ Mpc$^{-1}$ is about 2.9%. With $\sigma_v=150$ km/s, the M25-corrected value is $69.7\pm2.6$ compared with $71.5\pm2.6$ for the older C15 reconstruction, so the result flips the sample from agreement with the distance ladder to agreement with the CMB.
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The central claim is that the observed gravitational-wave strain from a compact binary merger contains two separable cosmological observables: the luminosity distance dL from the oscillatory part of the signal, and the integrated cosmological memory (ICM) offset from the post-merger step. The ICM amplitude follows N+ = h⊕/(3 E^{2/3}(z0)) ∫0^{z0} (1+z)/E^{4/3}(z) dz, where E(z)=H(z)/H0; because this integral weights the expansion history differently than dL does, the pair (dL, R=N+/h⊕) lands on a unique point in the R–dL plane for each expansion history, fixing both distance and redshift for a single event. The authors demonstrate the extraction in simulation: standard Bayesian parameter esti
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The paper claims that linear matter clustering at scales near k=0.1 h/Mpc is plausibly suppressed relative to the GR/ΛCDM prediction, with an effective gravitational coupling Geff=G/(1+Aξ) where ξ∝(1+z)/k². Using a joint MCMC analysis of 35 uncorrelated fσ8 measurements, cosmic chronometer H(z) data, Pantheon+ supernovae, and CMB power spectra and lensing, the inferred amplitude A=4425±2000 (equivalently B=0.36+0.14−0.12) gives a 2.2σ preference for a non-zero scale-dependent term. The suppression is stronger during the matter-dominated era than in the dark-energy-dominated epoch, and the derived S8=0.831±0.011 matches the CMB-inferred value without exacerbating either the S8 or H0 tensions.
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The central claim is that the relation $L_\nu = \kappa L_X^\beta$, tying a Seyfert galaxy's neutrino luminosity to its intrinsic 20–50 keV X-ray luminosity, turns individually detected neutrino sources into standardizable candles. Because the observed neutrino flux then scales as $F_\nu \propto F_X^\beta d_L^{2(\beta-1)}$, any slope $\beta\neq 1$ makes the neutrino flux carry distance information: comparing twelve sources at different redshifts constrains $H_0$ once a non-redshift distance fixes the absolute scale. The joint posterior over ($H_0$, $\beta$, $d_{\mathrm{NGC\,1068}}$) yields $H_0 = 49^{+40}_{-30}\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$ and $\beta = 0.67^{+0.16}_{-0.25}$, with the calorimetric value $\beta = 1$ excluded at about $2\sigma$. The result is consistent with both the CMB value and the Cepheid-supernova value at $1\sigma$, so it does not yet adjudicate the Hubble tension, but it demonstrates that a neutrino-only rung of the distance ladder is observationally viable.
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On the paper's own terms, the central discovery is a reframing: the 'Hubble tension' between local distance measurements and the CMB is not primarily a conflict over the expansion rate H0 but a conflict over the standardized peak absolute magnitude M_B of Type Ia supernovae. The first two rungs of the distance ladder measure M_B = -19.204 ± 0.030 from 17 nearby Cepheid-calibrated host galaxies, with no cosmological assumption. The same supernova population, inserted into CMB-constrained standard cosmology and fit over redshifts 0.04 to 1, demands M_B = -19.430 ± 0.013. The 0.23-magnitude gap is about 7 sigma and survives any smooth change in the late-time expansion history; fitting the magni
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For an axisymmetric Bianchi type I background with freely decaying shear and isotropic pressure, the fractional luminosity-distance quadrupole AD(z) is fully determined through relative order z^2 by the present directional expansion contrast BH0 and the background deceleration and jerk parameters: AD(z) = -BH0 + (2q0 - 1) BH0 z / 2 + (5 - q0 - 18q0^2 + 6j0) BH0 z^2 / 12 + O(z^3, BH0^2). The formula separates two physical contributions: the direction-dependent redshift–affine-parameter mapping, which dominates at low redshift, and the Jacobi-focusing term, which first enters at order z^2. In the minimal model the direct quadrupolar Ricci focusing vanishes, while isotropic Ricci focusing contr
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The authors establish, using analytic arguments, that a mass-varying dark matter model with one bare potential V(φ) and one coupling scale M can generate an early dark-energy-like peak near matter-radiation equality and a late-time apparent phantom crossing near matter-dark-energy equality. The early peak's amplitude is set by the ratio m(φi)/m(φ0) − 1, its timing by the curvature of m(φ), and the late-time crossing is driven by the bare potential pushing the field at low redshift—exponential potentials doing this most naturally. Since both effects stem from the same mass function m(φ), the same range of M controls both, and the timing tracks the background evolution rather than separate ene
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The paper's central claim is that quantum corrections derived from Weyl-Wigner phase-space mechanics can dissolve the Hubble tension. Starting from a minisuperspace action and the Wheeler-DeWitt equation, it identifies the classical potential as a sum of powers of the scale factor and computes the effective quantum potential induced by a sinusoidal Wigner function W(x,k;τ)=g(x;τ) sin(μ k x). Each power x^{−κ} in the potential is rescaled by a factor b_κ(μ)=2κa_κ μ^{−κ}[(2−μ)^{−κ}−(2+μ)^{−κ}], which modifies the matter and radiation energy densities in the Friedmann equation. The result is an effective Hubble parameter h̃(x) that sits at about 0.673 at last scattering and rises smoothly to ab
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The central claim is that the entropy-area relation with a scale-dependent exponent Δ(x)=Δ0+Δ1/ln x, where x=(H1/H)^2, when fed into the gravity-thermodynamics first law on the apparent horizon, yields an exact analytic Hubble rate H(z). Combined fits to Hubble-rate measurements, type Ia supernova distances, baryon acoustic oscillations, and CMB shift parameters give H0 = 69.27^+0.62_-0.65 km/s/Mpc with Δ0 ≈ 2.4×10^-3 and Δ1 ≈ -0.65, implying Δ(0) ≈ 1.09×10^-4. The derived Δ(z) crosses zero at z_tr ≈ 100 (with broad uncertainties), connecting a negative-Δ early phase to a positive-Δ late phase. The model is fully consistent with the data but is not statistically preferred over ΛCDM (ΔBIC ≈ 7
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The central discovery is that a cosmological model in which the Gauss-Bonnet correction to the Wald entropy of the apparent horizon is sourced by the astrophysical history of black-hole formation and mergers fits the combined early- and late-Universe data better than ΛCDM, with the coupling parameter Cn = 0.435^{+0.150}_{-0.132}, a ~3σ phantom-side deviation from zero. The mechanism preserves the standard acoustic scale, leaving the primary CMB nearly unchanged, while the late-time expansion is enhanced enough to shift H0 upward by about 1.3 km/s/Mpc. The cost is a modest rise in S8, and independent growth probes (lensing and redshift-space distortions) are slightly worse-fit than in ΛCDM. T
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Applying the revised Pantheon+ host-mass magnitude corrections to the 52 affected H0DN Hubble-flow rows, with network covariance, redshifts, and velocities held fixed, yields H0 = 73.264 ± 0.806 km s⁻¹ Mpc⁻¹ and a 6.85σ tension with H0^CMB,ΛCDM = 67.24 ± 0.35. Replacing the full Hubble-flow rung or substituting DES-DOVEKIE (first application to a distance ladder) via a constant overlap offset produces values still near 73; neither update resolves the tension.
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The central claim is that the entropic generalized Chaplygin gas — a unified dark fluid with equation of state p = -A/ρ^α, plus an entropy perturbation that drives the effective rest-frame sound speed to zero — is consistent at the background level with the full set of late-Universe distance and growth data, and that its only significant effect is a late-time bending of the distance-redshift relation. The paper argues this deformation moves the joint posterior in (H0, Ωm, S8) almost exclusively along directions controlled by the expansion history: with one supernova calibration it substantially shifts H0 and improves the fit over ΛCDM; with another calibration the two models nearly coincide.
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On the paper's own terms, the central discovery is a negative one: after sorting all proposed explanations by the part of the cosmological inference chain they modify, no model simultaneously preserves the CMB acoustic peak structure, the baryon-acoustic-oscillation standard ruler, the supernova distance-redshift relation, lensing, structure growth, and local absolute calibration. Early-time models like early dark energy can shrink the pre-recombination sound horizon, which is the necessary direction for raising the CMB-inferred H0, but the paper's reference chains show that uncalibrated data keep the early component small (fEDE ≈ 0.02–0.04 with H0 ≈ 67.8–69.4) and only a direct local-H0 cal
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The central discovery is a simple ratio identity: with the CMB acoustic angular scale and the sound horizon fixed, a fractional increase in H0 equals the fractional increase in the dimensionless distance integral I ≡ ∫_0^{z★} dz/E(z). The paper splits I into a low-redshift part I<, directly constrained by data, and a high-redshift part I> that is not, and shows that Gaussian Process reconstructions of E(z) — built only from relative distances, with the BAO normalization marginalized — keep δI_</I_< below about 1.5 percent at 95% confidence for the combination of supernova and BAO data. Accounting for I> with smooth-model estimates yields δH0/H0 ≲ 2.07% (conservative) or ≲ 3.67% (maximally pe
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The paper's central claim is that a vEDE component, which boosts the expansion rate only while deuterium is finishing its burning around T_D ≈ 0.03 MeV, can reconcile the measured primordial deuterium abundance with the higher baryon density inferred from CMB data in early dark energy cosmologies. Quantified as ΔH/H(T_D) = 0.087 +0.036/−0.037, this boost preserves D/H at the high baryon density while barely changing helium-4, reducing the tension from 3.1σ to 0.7σ. The timing of the extra expansion is the key: a constant radiation excess raises helium-4 too efficiently and fails to reconcile the two baryon-density determinations.
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The paper shows that, in a flat ΛCDM cosmology, the constraining power of bright sirens on H0 is concentrated at low redshift when used alone: the luminosity distance becomes increasingly sensitive to Ωm and statistically noisier at higher redshift, so sources beyond z∼1 add little once Ωm is left free. This is quantified by a binned and a cumulative redshift analysis, both of which show a plateau in the H0 uncertainty around z∼1. When a mock BAO measurement is added, the H0–Ωm degeneracy is broken, the informative redshift range extends to z∼2, and far fewer events are required: roughly 20 bright sirens for σ_H0≈1 km/s/Mpc and 15 for σ_H0≈2 km/s/Mpc, compared with about 90 and 45 in the bri
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In a Planck-calibrated flat LambdaCDM background, matching the SH0ES measurement of H0 through a void-induced local expansion excess requires a present-day enclosed density contrast of about -0.44, roughly 50% deeper than the KBC benchmark of -0.3. A KBC-like void lowers the statistical tension from above 5 sigma to about 2 sigma, and the tension remains below 3 sigma only for voids with depths between about -0.64 and -0.22. Varying the dark-energy equation-of-state parameters w0 and wa over broad CPL ranges, including regions motivated by recent DES and DESI analyses, shifts the required depth by less than a percent, so dynamical dark energy cannot rescue a shallow KBC-like void. The paper
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On the paper's own terms, the central discovery is that a natural dark-matter–dark-energy interaction arises when the complex scalar potential is expanded near its maximum, and that this interaction makes the effective Hubble constant decrease with redshift in a way that matches the binned Pantheon supernova data. The key result is the closed-form solution ϵa = ϵa0 (1+z)^3 e^{-2δρ/σ0}, which shows the axion (dark matter) energy density is exponentially suppressed as the modulus displacement δρ grows; this suppression is what bends H0(z) downward. The best-fit value Δ = 0.00964 ± 0.00457 quantifies the effect, and the paper reports its statistical performance is between the empirical power-la
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Central claim: ~10^-18 solar-mass PBHs at 10^-3 of the dark matter density delay recombination by Δz≈64, translating to an 8.9% rise in the CMB-inferred H0. A fully evaporated PBH heats its surrounding gas independently of mass; abundance above 10^-2 would fully reionise at recombination. The 8.9% is nominal: grey-body factors and full CMB fitting lower the required fraction, leaving the tension not fully relieved.
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The paper's central claim is that the generalized mass-to-horizon entropy class, despite its additional parameters, is observationally forced back to standard Bekenstein–Hawking thermodynamics: the entropy exponent satisfies |m−1| ≲ 10⁻⁴ when the MHR coupling is fixed and ≲10⁻³ when the coupling is free, and the derived coupling and entanglement amplitude deviate from their ΛCDM values only along degeneracy directions. It further claims that the apparent resolution of the Hubble tension is an artifact: adding parameters absorbs the CMB–SH0ES discrepancy, pushing h to 0.70–0.71, but the Bayesian log-evidence is negative for every extension in every dataset combination (−16 ≲ Δ ln Z ≲ −1). The
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The central claim: apparent phantom crossing can arise from a well-defined interacting dark sector, not a fundamental phantom field. In the DADB model, the dark QCD axion's effective potential depends on dark-baryon density; the baryon mass varies as the axion rolls, falling before recombination and rising afterwards. This non-monotonic mass evolution fits the CMB while producing an apparent phantom crossing over the BAO/supernova epoch. Fitted to CMB, BAO, and recalibrated supernova data, the best model beats ΛCDM by Δχ²=-14.48 with three extra parameters. The same dynamics yields an early-dark-energy component peaking at ~0.8% of total density, too small to resolve the Hubble tension.
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The abstract reads: "the HN c-field dynamics is shown to be encompassed by the GCG equation of state through an equivalent modified scalar field theory." Concretely, Eq. (46) H²(φ)=H²(ϕ)-ċ²/3, together with the derived ρφ and pφ in Eqs. (57) and (60), and the tanh-deformation case with c_s²>0 for all scale factors. If correct, the creation field belongs to a broader scalar-field dark-sector family that can modify the late-time Hubble rate while keeping the effective fluid linearly stable.
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The central claim is that the six-parameter concordance model—with parameters Ωb h², Ωc h², θMC, τ, As, ns—continues to provide an adequate description of all CMB temperature and polarization power spectra through the 2020s. Planck measured seven acoustic peaks and troughs to ℓ ≈ 2500; the EE and TE spectra independently agree with the TT-derived parameters; gravitational lensing is detected at 40σ in temperature; and searches for primordial B-modes have only strengthened the upper bound to r < 0.036. The review regards the absence of any statistically significant departure from this model, apart from the H0 tension, as the summary finding of the past decade.
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On its own terms, the paper's finding is a hierarchy. In the baseline analysis, ΛCDM sits at a 5.4σ (ΔDMAP) tension with the locally calibrated supernova magnitude, and no contender closes the gap completely. The best performers are early-time mechanisms: axion-like early dark energy reaches a residual 2.5σ with −ΔAIC ≈ 23 and log-Bayes ≈ 10.5; early modified gravity, Rock'n'Roll, and NEDE cluster at 2.7–3.1σ. The varying-electron-mass model is the only non-early contender to pass the selection thresholds, at roughly 4σ; radiation and late-time groups stay near or above 4.5σ. Without ACT data, most radiation and recombination models recover to 3–3.5σ, so the preference for early dark energy
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The central claim is that, in a common statistical framework applied to the baseline CMB+BAO+SN dataset, the four early-energy models (axion-like early dark energy, cold NEDE, early modified gravity, and its Rock'n'Roll limit) are the only contenders that both reduce the residual calibration tension to the 2.5–3.6σ level and achieve strong joint-fit support over ΛCDM (−ΔAIC > 10 and ln BF > 3). A localized non-radiative contribution near matter–radiation equality is thus identified as the most effective mechanism, because it shrinks the sound horizon while leaving the detailed high-multipole CMB spectra and the low-redshift distance relation intact. The paper does not claim any model fully r
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In the phenomenological ξ IDE model the combination ξ + 3w_X is negative for every dataset combination examined, corresponding to energy transfer from dark energy to dark matter; the tightest constraint is ξ + 3w_X = −0.035 ± 0.023 (1.52σ from zero) for CMB + DESI DR2 + CC + Union3, so current data supply only a weak indication of a non-zero dark-sector interaction while Bayesian evidence continues to prefer ΛCDM.
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Joint analysis of DESI DR2 BAO with CC, SNIa and CMB distance priors yields H0 = 64.05 ± 0.27 km s^{-1} Mpc^{-1}, Ωm = 0.3264 ± 0.0043 and Ωk = 0.0088 ± 0.0016 (non-flat DGP) or H0 = 63.28 ± 0.25 km s^{-1} Mpc^{-1} and Ωm = 0.3303 ± 0.0036 (flat DGP). Both cases give ΔAIC ≳ 100 relative to ΛCDM, driven by the model’s inability to fit DESI BAO and CMB distance priors at once, and produce a delayed transition to acceleration at zt ≃ 0.41.
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The central result is an equation (Eq. 8) showing that, for a fixed sound-horizon calibration, the Hubble constant is determined entirely by the distance-duality parameter η, the supernova intercept M, and the sound horizon r_d—none of which depend on the late-time expansion history. This means no modification to late-time expansion alone can shift H_0 unless it also breaks distance duality. The paper then shows that the required ~8–10% duality violation is excluded because its two components are independently constrained to sub-percent and percent levels by current BAO, cosmic-chronometer, and CMB-temperature data.
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The heliosphere acts as a coherent, observer-side optical filter: plasma refractive-index gradients across the heliopause produce a weak-lensing flux enhancement δ_helio of order 0.08 for upwind lines of sight at 550 nm, enough to shift the local distance ladder by several percent and thereby contribute 3–8 percent of the Hubble tension once anisotropy and calibration effects are included.
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Angular cross-correlations of distance indicators with galaxy redshift catalogues, analysed jointly in redshift space and in observed-distance space, break the H0–ΔM degeneracy and thereby constrain a constant calibration bias without relying on primary distance-ladder anchors.
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When linear dark-energy perturbations are treated consistently, the smooth error-function ECDM model is fully compatible with current precision CMB, BAO and supernova data and simultaneously lowers the Hubble tension relative to flat ΛCDM.
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Joint strong-lensing constraints on the sign-changeable interaction Q = 3 beta H rho_dm q yield best-fit values Omega_dm0 = 0.253^{+0.018}_{-0.004} and beta = -0.83^{+0.10}_{-0.08}. This large negative beta implies dominant energy flow from dark energy to dark matter, producing a constantly accelerating Universe whose deceleration-parameter zero-crossing occurs at z_t = 2.33 rather than the Lambda-CDM value 0.64.
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With ten years of DUNE exposure the experiment can set 3σ upper bounds on the long-range potential of order 10^{-14} eV in the eμ and eτ sectors, thereby excluding previously unexplored regions of the (mZD, geff) plane down to geff ≲ 10^{-28} at mZD ∼ 10^{-35} eV; the same underlying active–dark mixing simultaneously produces neutrino self-interaction strengths G4 u_eff ∼ 10^9–10^{10} GF that are cosmologically relevant for the Hubble tension.
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With Planck 2018 + DESI DR2 + DESY5, both discrete and continuous unimodular diffusion models identify a transition phase at intermediate cosmic times and yield slight evidence relative to ΛCDM according to ΔDIC (especially when curvature is allowed), while remaining non-decisive on the sign of Δ ho_Λ and not significantly alleviating the H0 tension.
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In two physically motivated k-essence cosmologies the Planck–late-Universe Hubble tension falls from 5.89σ in ΛCDM to 0.14σ (dilaton) and 0.69σ (tachyon) once all late-time probes are combined; the reduction is stable across every independent late-time combination and occurs without dataset-dependent retuning of the k-essence parameters.
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When constrained by late-time H(z), SNe Ia, DESI DR2 BAO, and an RSD growth compilation with free sound horizon, none of the three holographic-inspired models significantly alleviates the Hubble tension. Holographic dark energy is driven to c ≃ 1 (near the de Sitter boundary), agegraphic dark energy to n ≃ 2.8, and Ricci dark energy to γ ≃ 0.53–0.55 with Ωm0 ≃ 0.215–0.219; holographic dark energy is the most balanced of the three, yet current data do not decisively prefer it over ΛCDM.
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Using Planck CMB data together with DESI BAO and multiple supernova catalogues, dynamical dark energy continues to be preferred at similar significance in every extended model examined. Curvature remains consistent with zero, though a 2.2-sigma hint for positive Omega_k is strongly reduced once dynamical dark energy is allowed. Effective neutrino number stays compatible with the standard value while the upper limit on total neutrino mass ranges from 0.06 eV to 0.2 eV depending on the model. No primordial tensor modes are detected and the spectral index shows model dependence that can be partly absorbed by allowing small runnings, yet none of the extensions resolve the Hubble tension.
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Applying YY isochrones to a sample of 247,103 stars with LAMOST spectroscopy and Gaia parallaxes, then restricting to metal-poor alpha-enhanced objects with consistent FLAME ages, produces a final catalog of 155,600 stars within 5 kpc. MCMC reconstruction of the latent age distribution gives an oldest-star age A_star of 13.73^{+0.18}_{-0.15} Gyr. This matches the 13.6 Gyr expected in CMB-calibrated Lambda-CDM under the assumption that the first long-lived stars formed 0.2 Gyr after the Big Bang, thereby casting doubt on pre-recombination solutions to the Hubble tension that imply a cosmic age of only 12.9 plus or minus 0.2 Gyr.
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The f(T,B) model with the chosen power-law ansatz reproduces the observed expansion history, yields an improved AIC score on the CC+PPS combination relative to ΛCDM, exhibits phantom-divide crossing, and produces an H0 value that partially relieves the tension between early- and late-time measurements.
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Moving from ΛCDM to EDE increases the inferred α_s: once the acoustic angular scale θ_s is fixed, EDE increases the diffusion-to-acoustic angular scale ratio θ_d/θ_s, and the shift in α_s compensates this extra damping by increasing small-scale power.
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The exponential infrared f(T) model admits two distinct solution branches. Model I behaves like phantom dark energy and reduces the Hubble tension relative to Lambda CDM but is still disfavoured by the combined dataset. Model II produces a negative-to-positive transition in the effective torsional dark-energy density and is decisively ruled out. This exclusion stems from the interplay between background and perturbation constraints: once distance measurements fix the expansion, the model forces correlated parameter shifts that degrade the CMB damping tail fit and drive the optical depth to unphysical values.
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The paper's central claim is that a single 'high-τ' prior, τ = 0.11 ± 0.006, imposed in place of the standard low-multipole CMB polarization likelihood, makes ΛCDM concordant with the full set of current distance and clustering measurements. Within this universe, the sum of neutrino masses is inferred as Σmν = 0.10^{+0.04}_{-0.05} eV (68% CL), which the authors describe as the first 2σ cosmological detection of a positive, physical neutrino mass in ΛCDM; the lensing-driven preference for 'negative' neutrino mass disappears. The same prior raises the CMB Hubble constant to H0 ≈ 68.9 km/s/Mpc, matching the galaxy-clustering value and reducing the Hubble tension to 4.4σ, and brings predicted BA
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When the scalar potential is purely quadratic (μ=0), the fractional model with dynamically evolving G and H becomes the only variant that is both statistically competitive with ΛCDM and dynamically consistent: it yields an overdamped relaxation timescale τ_rel≈9 Gyr, well-constrained fractional exponents, and late-time cosmographic functions that closely track but do not coincide with those of ΛCDM, while the full quartic model is disfavored by BIC and by parameter degeneracies.
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A minimally coupled three-form with a Gaussian potential is a viable, competitive description of the cosmic expansion history. It is mildly preferred over ΛCDM precisely for the most tensioned early-plus-late combination (CMB+DESI BAO + Pantheon+SH0ES), becomes neutral for the less-tensioned early-plus-late set, and is disfavoured or inconclusive when early-only or late-only data are used. The dynamics produce a characteristic phantom phase at intermediate redshifts while recovering cosmological-constant behaviour at early and late times.
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When a dynamical dark-energy fluid is placed in a Bianchi Type-V spacetime, the residual shear density couples to the expansion history and to linear growth in such a way that simultaneous late-time measurements of distances and structure growth are better accommodated, thereby lowering the statistical tension between local and early-universe determinations of both H0 and S8.
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In a compact seven-route covariance summary, combining the Cepheid--SN Ia route with three level-1 alternatives (TRGB, JAGB, and Mira) and three level-2 alternatives (SBF, Tully--Fisher, and SNe II) gives H0=73.30±0.92 km s^{-1} Mpc^{-1}, still 5.6σ above Planck base-ΛCDM.
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Localized FRBs supply a precise dispersion measure-redshift relation that models the intergalactic medium electron density tightly enough to deliver independent low-redshift H0 values competitive with other probes and to constrain dark energy equation-of-state parameters, while current samples already demonstrate this utility and future surveys will deliver more stringent limits on cosmic acceleration.
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Within the symmetric teleparallel framework, the logarithmic f(Q) model infers intermediate values of the Hubble constant between the Planck and SH0ES benchmarks for all combinations of cosmic chronometers, Type Ia supernovae, and BAO data, while both models remain statistically competitive with Lambda CDM and the logarithmic variant shows lower AIC and BIC values.
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Current observations do not generically exclude sterile neutrinos, but rather place strong pressure on fully thermalized or highly populated scenarios, highlighting the importance of production history and phase-space distribution when interpreting cosmological constraints.
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The energy density of the hybrid dark energy model is formed by combining the contributions from a generalized length-time cut-off, reducing to the usual holographic and new agegraphic forms in the appropriate limits. In both interacting and non-interacting scenarios with cold dark matter, the model parameters are fitted to observational data, and the resulting cosmology reproduces the observed expansion history while keeping the Hubble tension low.
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The paper establishes that the Hubble-constant discrepancy persists whether or not early constraints use Planck CMB and whether or not late measurements use a full three-rung distance ladder, and that pure early-Universe sound-horizon solutions and pure late-Universe absolute-magnitude solutions are each blocked by no-go constraints, leaving interacting dark energy (combining early and late modifications) or new physics at the inhomogeneity-to-homogeneity transition as the remaining reviewed options.